1. Field of the Invention
The cosmetic compositions of this invention are particularly useful for preparing antiperspirant sticks and deodorant sticks.
2. Description of the Related Art
Gelled antiperspirant compositions for use in preparing transparent antiperspirant sticks are known. Typically, they will contain an antiperspirant, a solvent and a gelling agent, although other ingredients such as perfumes, coloring agents, antibacterial agents and emollients may be present.
Gelled deodorant compositions using sodium stearate and propylene glycol for preparing non-transparent deodorant sticks are known. As deodorant sticks, they generally function in one of two ways. Either they contain a strong fragrance such as a perfume which masks body odor caused by bacteria which multiply using perspiration as a nutrient medium, or they provide a hostile environment for bacterial growth because they contain an anti-bacterial agent and they are strongly alkaline.
It is impossible to make acidic gelled sticks using sodium stearate and propylene glycol base, because these compounds are not compatible with acidic antiperspirant salts. Sodium stearate no longer functions as a gelling agent in propylene glycol at acidic pH. Therefore, commercial deodorant sticks which have an acidic pH are not available except as opaque, antiperspirant sticks. Clear, transparent, deodorant sticks having an acidic pH are not available due to formulation difficulties.
DBMSA (dibenzylidene monosorbitol acetal) is particularly favored as a gelling agent in transparent gelled sticks. However, DBMSA is unstable in the presence of acids and hydrolyzes to form benzaldehyde. Benzaldehyde has an almond like odor which, while not necessarily unpleasant, is undesirable because it indicates the hydrolytic decomposition of DBMSA which is generally accompanied by decreased color and odor stability.
Antiperspirant compositions contain astringent aluminum or zirconium compounds or complexes or mixtures thereof. Usually the aluminum or zirconium compounds will take the form of astringent salts.
Such compounds are of a class well known in the art. They are described, for example, in Miller and Hoag, Personal Care Products, Handbook of Nonprescription Drugs, 5th Ed., Chapter 19, pages 397-417 (American Pharmaceutical Association, 1986). Aluminum compounds are described in U.S. Pat. Nos. 3,887,692; 3,904,741 and 4,359,456; and in British Patent Specifications 2,048,229 and 1,347,950. Zirconium compounds are described in U.S. Pat. Nos. 3,679,068 and 4,120,948. All of these citations are incorporated herein by reference. Attention is also directed to the Antiperspirant OTC Monograph which discloses antiperspirant salts commonly employed in antiperspirant compositions.
Many of the commonly employed aluminum or zirconium salts are acidic and, as aforesaid, DBMSA is unstable in acidic compositions. Much effort has been expended to stabilize DBMSA in acidic compositions against hydrolytic decomposition to benzaldehyde and other products.
U.S. Pat. No. 4,719,102 describes the use of various stabilizing agents such as N-(2-hydroxyethyl) fatty (C.sub.8 -C.sub.12) acid amide, magnesium sulfate, zinc acetate and hexamethylenetetramine. The last three of these compounds are also described as stabilizers in U.S. Pat. Nos. 4,518,582 and 4,720,381.
U.S. Pat. No. 4,725,430 describes the use of N-(2-hydroxyethyl) acetamide, alone, or combined with one or more of magnesium sulfate, zinc acetate, N-(2-hydroxyethyl) cocamide and hexamethylenetetramine as stabilizers in ethanolic compositions.
U.S. Pat. No. 4,722,835 describes the use of basic metallic salts such as calcium hydroxide and potassium carbonate as stabilizers for antiperspirant stick compositions. The compositions of the patent include 1 to 50% of what are described as small, polar organic and organic compatible compounds such as morpholine, pyridine and acetic acid as well as ethanol, propanol and butanol. The compositions may also contain less reactive alcohols which are secondary or long chain primary alcohols, such as isopropanol, isobutanol and 1,2-butylene glycol. The compositions are described as opaque.
Such stabilizing agents as have heretofore been utilized have not proved to be completely satisfactory principally due to discoloration and/or lack of clarity.
Other U.S. Patents describing the use of DBMSA as a gelling agent include 4,137,306; 4,154,816; 4,720,381; 4,781,917; 4,346,079; 4,822,602; 4,822,603; and 4,816,261. Foreign patent documents which relate to such compositions include Japanese Patent Publication 23170/88, which describes the use of urea as an anti-gelling agent, and European Patent Applications 0272919 and 0274267.
Many of these patents describe the use of water and lower monohydric alcohols, such as ethanol, as solvents. Such solvents are best avoided in gel stick compositions because sticks containing a high concentration of alcohol have a tendency to shrink due to evaporation of the alcohol. Additionally, it is difficult to prepare a clear antiperspirant stick due to the high temperatures required to solubilize DBMSA in alcohol. Water and ethyl alcohol are especially unsatisfactory solvents because they are very reactive, increase the rate of hydrolysis of DBMSA and heighten the almond odor. They also reduce stick hardness and increase tackiness.
As will be understood from the following description, the compositions of this invention are substantially anhydrous and substantially lower aliphatic monohydroxy alcohol free and yet, are highly transparent i.e. clear. Small amounts of water and/or alcohol can be added to the compositions of the present invention without adversely affecting stability. However, the compositions become more and more difficult to manufacture if alcohol is present. Additionally, too much water may cause a loss of clarity. Thus, although operative, the inclusion of alcohol and water in the compositions of the present invention is not preferred.
"Substantially free" relative to the water and lower monohydroxy alcohols as used herein means the composition contains less than about 5% and preferably 0% of such materials. The term does not include the presence of bound water.
As used in this description and claims the term "stable" means that samples of the product, in stick form, when stored for one month at 104.degree. F. will not exhibit a noticeable or objectionable benzaldehyde odor or color instability indicative of hydrolysis of DBMSA and will retain stick transparency and stick shape.
The term "lower aliphatic monohydroxy alcohols" means alcohols containing up to six carbon atoms such as methanol or ethanol.
The compositions of the present invention are transparent to the transmission of light. By transparent is meant that sufficient light passes through the gel sticks of the present invention to enable an observer to see without difficulty an image, e.g., lettering, placed immediately behind and in contact with the gel stick.
The compositions of this invention take two principal forms. In one form, they are useful for preparing antiperspirant sticks. In the other, they are useful for preparing deodorant sticks. For the former utility, they are principally characterized in that they contain an antiperspirant amount of an acidic antiperspirant soluble in the composition. For the latter utility, they contain up to about 8% of such antiperspirant together with an odor masking perfume and/or an antibacterial agent.